White horehound (Marrubium vulgare) is a member of the mint family with small white flowers and downy, silver-green, and distinctly bitter leaves. It has been used as a cough and cold remedy since ancient Roman times¹ and appears in Anglo-Saxon manuscripts as a treatment for respiratory complaints².

Horehound is both an expectorant and a spasmolytic: it helps shift tough, sticky phlegm from the airways while simultaneously easing bronchial spasm³. Historically, the influential seventeenth century herbalist Nicholas Culpeper noted its use for expectorating stubborn phlegm⁴, and the late-nineteenth century north American Eclectic physicians observed its pronounced stimulant action on the laryngeal and bronchial mucous membranes⁵. Horehound is now a common ingredient in throat lozenges, and it was the top-selling herbal product in the US market from 2013 to 2019⁶.

Horehound can help in conditions such as acute and chronic bronchitis, dry coughs, catarrh, sinusitis, laryngitis, whooping cough and asthma^7,8. It acts as an expectorant, spasmolytic, anti-inflammatory, and is mildly sedative⁹.

As with most herbs, some cautions apply: horehound is contraindicated in pregnancy due to emmenagogue and potential abortifacient effects¹⁰, and very large quantities may provoke arrhythmia or act as a mild laxative^1,11.

Aside from that, for a herb that has been soothing inflamed airways since antiquity, horehound remains relatively under-appreciated in modern practice and deserves a place in the modern dispensary.

References

1. Balch PA, Bell S. Prescription for herbal healing. 2nd ed. Penguin; 2012.
2. Watkins F, Pendry B, Corcoran O, Sanchez-Medina A. Anglo-Saxon pharmacopoeia revisited: a potential treasure in drug discovery. Drug Discov Today. 2011;16(23-24):1069–75.
3. McIntyre A. The complete herbal tutor. Aeon Books; 2019.
4. Culpeper N. Culpeper’s complete herbal. Foulsham & Company Limited; 1975.
5. Felter HW, Lloyd JU. King’s American dispensatory [Internet]. 1898 [cited 2026 May 19]. Available from: https://www.henriettes-herb.com/eclectic/kings/marrubium.html
6. Smith T, Majid F, Eckl V, Morton Reynolds C. Market report. HerbalGram. 2020;131:52–65
7. Alfs M. 300 herbs: their indications and their contraindications. Aeon Books; 2022.
8. Menzies-Trull C. Herbal medicine keys to physiomedicalism including pharmacopoeia. 3rd ed. Faculty of Physiomedical Herbal Medicine; 2022.
9. Bone K, Mills S. Principles and practice of phytotherapy. 2nd ed. Elsevier Health Sciences; 2013.
10. Aćimović M, Jeremić K, Salaj N, Gavarić N, Kiprovski B, Sikora V, et al. Marrubium vulgare L.: a phytochemical and pharmacological overview. Molecules. 2020;25(12):2898.
11. Duke JA. Handbook of medicinal herbs. 2nd ed. CRC Press; 2002.

Image: Bouquet.; Chailli, Jacques; Delachaussée.; Marchand, J.; Redouté, Pierre Joseph; Rousseau, Jean-Jacques – https://www.biodiversitylibrary.org/pageimage/6164719